ND SatCom SKYWAN IDU 1070, Manual

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38 Network Design and Engineering Guide 2010-10-26
General Carrier Design
Essential SkyWAN
®
Satellite Link Layer Features
Scenario 2
Both IDU1 and IDU2 are configured for stream mode Normal . The traffic mix (see figure 2-21)
consists of:
- A real-time IP based PC application with a bidirectional bandwidth requirement of 128
kbps between these two stations.
- Additionally 2 parallel voice calls served by Sky WAN
®
FAD real-time service should be ac-
tive between the stations.
Figure 2-21 Throughput Scenario 2
Effect
Due to the fact that a real-time service is used for the PC application, 10 out of 12 available
stream slots are already consumed by this application. If there are in addition two parallel voice
calls between IDU1 and IDU2, all available stream slots would be allocated. Now any additional
stream request would be blocked even if there are still unrequested slots outside the common
stream pool.
In this scenario the current traffic is not guaranteed for IDU1 and IDU2 because with stream
mode ’Normal’ the guaranteed throughput does not apply to streaming slots. If the common
streaming pool is already used by other stations the real-time PC application might be blocked
due to insufficient streaming bandwidth. Only additional non real-time traffic on IDU1 or IDU2
would benefit from the guarantee.